The Morris Arboretum is a zoological park not for animals but for more static creatures: shade trees, conifers and shrubs. Some of the most interesting and precious species of temperate woody plants on the planet have come together here to shape its rolling 166 acres on the northwestern edge of Philadelphia. It is hard to imagine a more bucolic city neighborhood.

By a sylvan stream, its lanky executive director, Paul Meyer, points out a pair of bald cypress trees that stretch 50 feet into the winter sky. He collected them as cones in 1976, on a visit to a state park near the Delaware shore that is the northernmost range of this native swamp conifer. They mark the span of one man’s life, so far, in the company of trees.

But it is to another specimen that he wants to direct my attention: a tree sacred to Japanese lore, the katsura. With age, its limbs grow into muscular, wrinkled boughs that extend sideways.

The Morris katsura sits on a knoll, unfurling its branches like a stop-motion sea monster from an old B-movie. The tree is about 120 years old and dates to the institution’s origins as the private estate of brother and sister John and Lydia Morris, prominent Quaker philanthropists in the well-heeled neighborhood of Chestnut Hill.

Trees that have exfoliating bark take on a special value in the winter. This is an old specimen of the paperbark maple. (Adrian Higgins/The Washington Post)

They left it in 1932 to the University of Pennsylvania, and in the ensuing decades it has become everything you want an arboretum to be: a place of biodiversity, scientific research and beauty. More than 130,000 visitors pass through its gates each year, but only the hardy souls are found on its trails on a freezing winter’s day.

We are in the bone-chilling back end of winter, when trees are dead or deadlike, right? Wrong. Someone once calculated that a mature elm tree might have 7 million buds at this time of year, waiting patiently for spring. And consider those buds, each encasing a flower or a leaf that is embryonic but already formed, like a butterfly in a chrysalis preparing to break free and spread its wings. The buds formed over the summer at the base of every leaf stalk. They were there when the leaves dropped, but even then we didn’t see them.

An expert such as Meyer can identify a tree by its buds. Nature writer Rutherford Platt, writing in the 1940s, said the best way to distinguish a slippery elm from an American elm is by the winter buds — the trees look too similar in growth. Some buds are shaped like spear tips, others like turbans; some are sticky, others furry, and all of them are wrapped in casings or scales that are distinct as well. Platt found the pointed buds of the shadblow serviceberry the prettiest. The scales are a red-brown and curved and give the effect of a candle flame, he noted.

So the February landscape is full of bud ornament and variety, but the problem with trees is that they are so big, we don’t see them. (Recognizing this, the Morris Arboretum has built a highly engineered aerial walk amid a canopy of chestnut oaks.)

The katsura flowers are small, but each is defined by eight carmine-red stamens. When they appear in April ahead of the leaves, the canopy glows with a rosy haze, Meyer said. “It’s subtle, but once your eye is into it, it’s really beautiful,” he said.

But we are getting ahead of ourselves. Between then and now, trees shift their mode of being, of which rising sap is just a manifestation. In late winter and early spring, they are being drawn from their winter dormancy into a new cycle of growth. This is spurred by warmth, but only after each tree has received its required minimum period of cold. This differs by species, and the earliest of bloomers simply need a short chilling period and are coaxed into life by relative mildness. One example of a precocious bloomer is the yellow-flowered Chinese witch hazel, now ablaze by the arboretum’s visitor center.

Elsewhere, Meyer took me to see specimens of the Japanese cornel dogwood (Cornus officinalis), whose buds, about the size of capers, were already beginning to open to reveal the golden petals beneath. This is a bit earlier than the more familiar and similar cornelian-cherry dogwood (Cornus mas). One penalty for visiting such a place is that the gardener pines for species and varieties that just haven’t made it into the mainstream commercial nursery trade.

The arboretum brings visitors into the presence of trees that are a century old, or more, such as this Blue Atlas cedar. (Adrian Higgins/The Washington Post)

The filbert or hazel (quite different from the witch hazel) is an interesting winter tree because its pollen-bearing catkins are tight and short after leaf drop but are now elongating and preparing to open. Gardeners know the European filbert, particularly the contorted form, but Meyer showed me a grove of a Chinese species collected on an expedition in the mid-1990s called the Farges hazelnut (Corylus fargesii).

The catkins are a rich chocolate-brown and spectacular in a subdued fashion, clustered in bundles of half a dozen or so. “These look as if they have started to break dormancy,” Meyer said. “I suspect that less than a week of warm weather, and these male catkins would be in full bloom.”

There is something about seeing an old and beautiful tree that is just so affirming of nature and life. To be its steward is a privilege.

I asked Meyer why he thought such trees resonate so much. “I think their longevity, their majesty. I love the idea that you can make a difference by planting a tree. Think of the impact you could have if you plant a white oak this spring, and if that shades your home, not just for you, but for 200 years.”

While you think about spring planting, start looking at trees in the winter, their silhouette, their buds, their shifting in and out of dormancy.

Observing old trees now is like watching a diva waiting in the wings to go onstage, at a moment that is both thrilling and perilous. But maybe the anticipation is a key part of the event. Maybe the trees are onstage already; we’re just not in our seats.

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